Cold-pressing process and apparatus



Oct. 25, 1966 H. SCHROM 3,280,613

COLD-PRESSING PROCESS AND APPARATUS Filed Jan. 17, 1963 2 Sheets-Sheet l INVENTOR #417 "1 1 Mclde! ATTORNEY Oct. 25, 1966 H. SCHRGM 3,280,613

COLD-PRESSING PROCESS AND APPARATUS Filed Jan. 17, 1963 2 Sheets-Sheet 2 INVENTOR ATTORNEY United States Patent Ofiice 3,280,613 Patented Oct. 25, 1966 4 Claims. c1. 72 s44 The present invention relates to cold-pressing.

More particularly, the present invention relates to process and apparatus which is used for cold-pressing slugs of metal or the like, especially of steel, into the configuration of a desired article such as, for example, a sparkplug housing.

At the present time considerable difliculties are involved in cold-pressing processes and apparatus of this type. Thus, the slug which is used for this purpose is generally cut from a cylindrical rod, and the slug is unavoidably deformed when it is cut from the rod so that the cross section of the slug becomes oval and does not remain of the same cylindrical cross section as the rod from which it is cut. Furthermore, the end faces of the slug do not remain flat and parallel to each other respectively in planes normal to the axis of the rod, as a result of the cutting of the slug from the rod. As a result, when such a slug is placed in a die, it provides a reaction force on the punch which advances into the die to deform the slug therein which shifts the punch with respect to the die so that the coaxial relationship between the punch and the die is not maintained, wit-h the result that the finished product does not have a uniform wall thickness.

Moreover, where the slug is to be deformed by the punch and die into a cup-shaped article of relatively complex configuration having, for example, several steps at its outer and inner surfaces, it is not possible at the present time to carry out the entire process in a single step, and it becomes necessary instead to provide several different operations before the final configuration of the slug is obtained, together with heat-treatment of the slug between these operations.

It is accordingly a primary object of the present invention to provide a process and apparatus which will reliably maintain the coaxial relationship between the punch and die of the apparatus even though the slug has an irregular, non-cylindrical configuration.

Another object of the present invention is to provide a process and apparatus which make it possible for the slug to be deformed into the final, desired configuration in a single operation.

It is also an object of the present invention to provide an apparatus of the above type with a structure which will operate automatically to enable the successive operations of the press to be interrupted in the event that during any one operation the process does not go forward in a normal manner, so that in this way the punch Will be prevented from moving along its working stroke if during the preceding return stroke of the punch the operations did not proceed in the normal manner.

It is also an object of the present invention to provide for a process and apparatus of the above type, a structure which while guaranteeing the coaxial relationship between the punch and the die will also function to strip the final article from the punch during the return stroke of the latter.

It is also an object of the present invention to provide a process and apparatus capable of accomplishing all of the above objects and at the same time characterized by great simplicity and reliability.

With these objects in view the invention includes, in a cold-pressing apparatus, a die means which has an inner annular surface surrounding the axis of the die means and defining a cavity of the die means. An elongated punch means is coaxial with the die means and is movable along the axis thereof into and out of the cavity. In accordance with the present invention a guide sleeve coaxially surrounds and slidably engages the punch means, and this guide sleeve extends into the cavity of the die means and slidably engages the inner surface thereof, so that as a result of the slidable engagement between the guide sleeve and the die means, on the one hand, and the guide sleeve and punch means, on the other hand, the coaxial relationship between the punch means and the die means is maintained during the deforming of a slug by the punch means in the die means, even if the slug has an irregular configuration when it is originally introduced into the die means.

According to the process of the invention, there is placed into a die cavity, which has a pair of end portions of relatively large and relatively small cross sectional area and an intermediate portion of intermediate cross sec-tional area between that of said end portions, a slug whose cross sectional area is substantially equal to that of the intermediate cavity portion so that the slug rests in the die between the cavity portions of intermediate and relatively small cross sectional area, and then the punch is advanced into the cavity to spread the material of the slug laterally into engagement with the die surfaces which define the cavity portions therein, the material of the slug being advanced in the direction of advance of the punch from the intermediate cavity portion into the cavity portion of relatively small cross sectional area and in a direction opposite to the direction of advance of the punch along the cavity portion of relatively large cross sectional area, and in accordance with the invention there is maintained in yieldable engagement with the end of the slug which is in the cavity portion of relatively large cross sectional area a guide sleeve which slidably engages the die in the cavity thereof and which slidably engages the punch to maintain the latter coaxial with the die. this sleeve yielding in a direction opposite to the direction of advance of the punch with the material which flows in the cavity portion of relatively large cross sectional area.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIGS. 1A and 1B respectively illustrate, in plan and elevation views, the configuration of a slug which is to be worked on with the process and apparatus of the invention;

FIGS. 2A and 2B show in a partly diagrammatic sectional elevation the press structure and the process of the invention, the structure being shown in FIG. 2A in the position which it takes just after the beginning of the working stroke of the punch and in FIG. 2B in the position it takes at the end of the working stroke of the punch; and

FIG. 3 is a partly section-a1 elevation illustrating the configuration of the article into which the slug of FIGS. 1A and 1B has been shaped with the process and apparatus of the invention.

Referring to FIGS. 1 and 2, it will be seen that the slug 1 from which the article shown in FIG. 3 is formed has, generally a diameter equal to the diameter of the intermediate portion 2a of the article 2 shown in FIG. 3, and

' it is coated with a lubricant, well known in the art, and it is then placed in the annular die means 3 which is illustrated in FIG. 2A. In order to simplify the manufacture of the die means 3 as well as the replacement of nonuniformly Wearing parts thereof, the die means 3 is made up of three separate rings 3a, 3b, 30 which together define the elongated cavity 4 of the die means, this cavity 4 passing through the die means 3 and being defined by an inner annular surface of the die means which surrounds the axis of the die means. The several rings 3a, 3b, 3c which make up the die means are centered with respect to each other in the annular die holder 5.

The'lower die ring 30 rests directly on the upper surface of the plate 6 or the press. The upper die ring 3a: is provided at its exterior surface 7 with an annular shoulder 8 which is engaged by the shoulder 9 of the die holder which does not engage the plate 6. The die holder 5 is formed along a plurality of axes 10 which extend parallel to the die axis 11 and which are uniformly distributed along a circle whose center is in the die axis 11 with a plurality of bores 12 which respectively receive the bolts 13 whose enlarged head ends rest on shoulders of the bores 12, as indicated at the lower portion of FIG. 2. The support plate 6 of the press is formed with threaded bores 14 which are respectively coaxial with the bores 12 and which threadedly receive the threaded ends of the bolts 13 so that the bolts 13 serve together with the die holder 5 to tightly hold the several rings of the die means 3 in engagement with each other and also properly positioned with respect to the support plate 6.

The opening which passes through the upper ring 3a of the die means 3 is of a polygonal configuration so that the cavity end portion 4a is of a polygonal configuration, and it will be noted that the cross sectional area of the cavity end portion 4a is relatively large while the cross sectional area of the cavity portion 40 is relatively small, and between these cavity end portions 4a and 4c there is an intermediate cavity portion 4]) which is of an intermediate cross sectional area. In the illustrated example the cavity portion 4a has the configuration of a regular hexagon. The upper edge 15 at the opening of the ring 311 is rounded, as indicated in FIG. 2. The intermediate cavity portion 4b is coaxial with and forms an extension of the relatively large cavity portion 4a, and this cavity portion 4b is cylindrical and of course is formed by an opening passing through the intermediate ring 3b. The diameter of the cylindrical bore 4b is somewhat smaller than the diameter of a circle which can be inscribed within the hexagon of the opening 4a. The edge 16 at the upper end of the opening 4b is also rounded.

The lower ring 30 has at the upper end of its bore 40 a rounded edge 17 which provides the bore 4c'with a diameter which becomes gradually smaller from the upper face of the ring 30 toward the lower face thereof in the region of the upper end of the bore 4c, and then where the remainder of the bore 4c joins the edge 17 this bore is of a cylindrical configuration. The diameter of the cylindrical portion of the bore 40, below the tapering portion 17 thereof, is substantially smaller than the diameter of the bore 4b of the intermediate ring 3b.

In order to provide a tight, sealed engagement between the several rings of the die means 3, the opposed faces 18 and 19 of the intermediate ring 3b are planar only at the I inner regions of these faces which surround the opening 4b, and the remainder of these faces have a frusto-conical configuration with the frustocones oppositely directed in the manner indicated in FIG. 2.

The support plate 6 is formed with a bore 20 which is of the same diameter as and forms an extension of the bore 40. Thus, the coaxial bores 4c and 20 form a single continuouscavity portion which receives an ejector punch 23 having a pair of annular projections 21 and 22 which slidably engage the surfaces of the bores 46 and 20, in the manner indicated in FIG. 2, and the punch 23 is coaxial with the die means and is capable of freely sliding axially with respect tothe die means along the cavitythereof as well as along the portion 20 of the continuous cavity 40, 20. At its upper end the ejector punch 23 has a central projection provided with a frustoconical portion 24a which is jointedat the tip of the projection 24 to a conical portion 24b, and it is this projection 24 which is directed toward the interior of the cavity of the die means 3.

During operation of the press the lower portion 25 of the punch 23 is gripped by a well known structure in such a way that the punch 23 maintained stationary in the illustrated position where the annular projection 21 is in an intermediate part of the bore :portion 40, so that the annular projection 21 forms the lower end of the cavity in which the slug 1 is shaped, and the clearance between the projections 21 and 22 with respect to the surface of the bore 40, 20 is such that during operation of the press while the punch 23 is maintained stationary in the position illustrated in FIG. 2 air can escape past the projections 21 and 22 while the material of the slug 2 is incapable of moving past the projection 21.

The press structure shown in FIG. 2 includes a main working punch 26 whose axis coincides with the axis 11 of the die means 3 sothat the axis of the punch 26 coincides withthe axis of the cavity 4. At its upper end the punch 26 has an enlarged elongated portion 28 of frustoconical configuration with the larger diameter of the portion 28 located at the upper end thereof, as viewed in FIG. 2, and the top face 27 of the punch 26 is directly engaged by the pressure plate 29 which is acted upon by conventional press structure well known in the art so as to be moved downwardly during the working stroke of the punch 26 and due to engagement at the face 27 of the punch 26 with the latter the plate 29 will advance the punch 26 downwardly during the working stroke thereof. The plate 29 is located at the end of an unillustrated plunger which is acted upon by any suitable means, for example fluid under pressure, so as'to be moved along working and return strokes, as is well known in the art. The plunger which is operatively connected to the plate 29 moves the latter along the axis 11 back and forthduring one cycle of operation.

The frustoconical portion 28 of the punch 26 is surrounded and engaged by a plate 31 which is formed with a frustoconical bore 30 mating with the portion 28 of the punch 26, and due to the relatively slight inclination of the frustoconical surfaces of the punch portion 28 and the bore 30 the plate 31 tightly grips the punch 26 at its frustoconical portion 28. The punch-gripping plate or ring 31 does not engage the working plate 29. The

ring 31 is formed with a plurality of bores 33 respectively extending along the axes-32 which are uniformly distributed about and located at equal radial distances from the axis 11, and these bores 33' of the grip ring 31 respectively receive the bolts 34 whose enlarged head ends engage shoulders of bores 33, as is apparent from the right portion of FIG. 2, and the pressure plate 29 is formed also along the axes 32 with threaded bores 35 which re-.

spectively receive the threaded ends of the bolts 34 so that through this construction the face 27 of the punch 26 is maintained at all times pressed tightly against the plate 29. Thus, the punch 26 is fixedly connected with the plate 29 and moves with the latterduring both the working and the return strokes thereof.

At its bottom, head end the punch 26 has an annular projection 36 whose diameter is only slightly greater than that of the shank 37 of the punch 26, and this annular projection 36 forms the uppermost of a series of stepped portions of the punch 26 which determine the configuration of the head end thereof. The stepped end projection 38 of the punch 26 has a pair of frustoconical portions 38a and 38b which are separated from each other by a cylindrical portion 380, and a second cylindrical portion 38d adjoins the lower end of the frustoc-onical portion 38b while a conical tip 388 adjoins the cylindrical portion 38d, and all of these portions of the punch 26 are coaxial so that in this way the head end of the punch 26 has the stepped configuration illustrated in FIG. 2. It will be noted that the frustoconical portions 380 and 38b taper in a downward direction, and the same is true of the conical tip 381:, so that the cylindrical portion 386 adjoins the small end of the frustoconical portion 38d and the large end of the frustoconical portion 38b while the cylindrical portion 38d adjoins the small end of the frustoconical portion 38b and the base of the conical tip 38e.

Approximately midway of its shank 37, the punch 26 is provided with an annular guiding projection 39 which is of a cylindrical configuration and which is of the same diameter as the cylindrical projection 36 at the head end of the punch 26. A guide sleeve 41 of the structure of the invention has a cylindrical bore 40 and this sleeve 41 coaxially surrounds the punch 26 and the inner surface of the guide sleeve 41 slida-bly engages the projections 36 and 39 so that these projections are slidably received within the bore 40 of the guide sleeve 41. The fit between the inner surface of the sleeve 41 and the outer surfaces of the projections 36 and 39 affords a very precise sliding cooperation while being fairly snug so that the punch 26 is very precisely guided by the inner surface of the sleeve 41. At its lower end the guide sleeve 41 has a thinwalled neck 42 which is also of cylindrical configuration, and the exterior surface of the neck 42 of the sleeve 41 has a very precise sliding fit with the upper ring 3a of the die means, the diameter of the exterior surface of the neck 42 being precisely equal to that of a circle which can be inscribed within the hexagonal bore 4a and located in a plane normal to the axis 11, so that in this way the exterior surface of the neck 42 has line-contact with the several flats or lands which define the inner surface of the ring 3a. Of course, the several lines of contact between the neck 42 of the sleeve 41 and the lands of the inner surface of the ring 3a extend parallel to the axis 11. During the deformation of the slug 1, which takes place during the working stroke of the punch 26 when it is advanced downwardly, as viewed in the drawing, the guide sleeve 41 is directly guided by the cooperation of the neck 42 and the inner surface of the ring 3a for movement coaxially with respect to the die means, and because of the engagement of the inner surface of the sleeve 41 with the projections 36 and 39 of the punch 26, this punch 26 is indirectly guided from the die means through the sleeve 41 so as to 'be maintained by the latter in a position precisely coaxial with the die means irrespective of any irregularities of the slug 1 which might otherwise tend to force the punch 26 angularly to a position where it was not precisely coaxial with the die means.

The guide sleeve 41 is formed adjacent its upper end, as viewed in FIG. 2, with a pair of diametrically opposed threaded bores 43 which extend radially with respect to the sleeve 41 along a common axis which is normal to the axis 11, and these threaded bores 43 receive a pair of screws 44, respectively, which have inner ends 44a projecting inwardly beyond the inner surface of the sleeve 41 and located at an elevation higher than the projection 39. The extent to which the screws 44 are threaded in the bores 43 is such that the inner ends of the projections 44a do not engage the shank 37 of the punch 26, and the upper surface of the projection 39 forms together with the screws 44 a limiting means which limits the extent of movement of the sleeve 41 downwardly, with respect to the punch 26, as viewed in FIG. 2, as will be apparent from the description below. The movement of the guide sleeve 41 upwardly with respect to the punch 26, as viewed in FIG. 2, is limited by engagement of the top face of the guide sleeve 41 with the bottom face of the gripping ring 31.

For a purpose which is described below, a stationary pivot 51, carried by the unillustrated plunger of the press, forms a support means which supports an elongated lever 52 for turning movement about an axis which is perpendicular to the axis 11, and this elongated lever 52 extends across the axis 11 in the manner shown in FIG. 2. A motion transmitting means is situated between and engages the lever 52 and the guide sleeve 41, and this motion transmitting means includes the pair of elongated rods 45 which are fixed to the top face of the sleeve 41, which extend parallel to the axis 11, and which pass freely through coaxial bores 46 and 47 respectively formed in the plate 29 and ring 31, the plate 29 being formed with a pair of bores 46 for the rods 45 while the ring 31 is formed with a pair of bores 47 coaxial with the bores 46, respectively, and through which the rods 45 respectively pass in the manner shown in FIG. 2. At their top ends the rods 45 are interconnected by a cross-plate 48 which is fixed in any suitable way to the top ends of the rods 45. The plunger which is operatively connected with the plates 29 in the manner described above is formed with a bore 50 which is coaxial with the die means and which guides for free movement along the axis of the die means an elongated pin 49 which has its bottom rounded end in engagement with the plate 48 and its upper rounded end 49a in engagement with the underside of the lever 52. Thus, the parts 45, 48, 49 form a motion transmitting means extending between and engaging the lever 52 and the sleeve 41, and with this construction any force acting downwardly on the lever 52 will be transmitted through the motion transmitting means 45, 48, 49 to the sleeve 41, while any upward force acting on the sleeve 41 will also be transmitted to the lever 52.

A yieldable means, diagrammatically indicated by the arrow P, urges the sleeve 41 downwardly, and this yieldable means P, which may take the form of any springs, hydraulic structure, or weights, acts directly on the lever 52 for urging the latter to turn downwardly in a counterclockwise direction, as viewed in FIG. 2, and through the motion transmitting means 45, 48, 49 the yieldable means P has its force transmitted from the lever 52 to the sleeve 41 so that in this way the sleeve 41 is yieldably urged in a downward direction. In the starting position of the parts the punch 26 is at an elevation higher than that shown in FIG. 2A, and in this starting position of the part-s the free end of the neck 42 of the sleeve 41 projects somewhat beyond the tip of the punch 26 while the ends 44a of the screws 44 are urged against the projection 39 with the force which is determined by the yieldable means P. In the particular embodiment shown in FIGS. 2A and 2B the yieldable means P is formed by an elongated spring 51' extending substantially parallel to the axis 11, connected at its upper end to the lever 52, and connected at its lower end to the plate 29 which is connected to the unillustrated plunger, as described above.

Of course, at the starting position of the parts, just before the punch 26 starts to move downwardly along its working stroke, the elevation of the punch 26 and the guide sleeve 41 is such that there is free access to the cavity 4 of the die means 3 so that the slug 1 can be dropped into the cavity, and when the slug 1 is introduced into the cavity of the die means 3 it will rest with one of its end faces 1' on the upper edge portion 17 of the bore 40, and it will be noted that the diameter of the slug 1 is substantially equal to that of the bore 4b, while the upper portion of the slug 1 at this time is located within the cavity portion 4a of relatively large cross sectional area.

During the initial part of the working stroke of the punch 26, the force of the yieldable means P will maintain the screws 44 in engagement with projection 39 so that the guide sleeve 41 will follow the movement of the punch 26 and will enter with the latter into the cavity 4. Thus, the exterior surface of the neck 42 of the sleeve 41 will be precisely guided by the hexagonal bore 4a, as described above, and the movement of the sleeve 41, which initially has its bottom end located in advance of the tip of the punch 26, as described above, will continue until this bottom end of the sleeve 41 engages the top face of the slug 1. Thus, the sleeve 41 will move into the die until the bottom face of the sleeve 41 engages and presses against the top surface of the slug 1 with the force of the yieldable means P. At this time the sleeve 41 will stop moving while the punch 26 will continue to advance along its working stroke, so that the projection 39 moves downwardly away from the screws 44, and when the tip of the punch 26 initially engages the slug 1, the parts will have the positions indicated in FIG. 2 to the left of the axis 11.

The force provided by the yieldable means P is smaller than the force required to deform the slug 1, so that as a 1 result the sleeve 41 will be maintained stationary by the slug 1 when the sleeve 41 initially engages the slug 1. During the continued advance of the punch 26along its working stroke, after its tip 38c has engaged the slug 1', the slug 1 is plastically deformed and the working of the slug 1 so that its material will flow to provide the article shown in FIG. 3 commences.

The head end 38 of the punch 26 presses into the material of the slug'l and forms in the latter a cavity whose configuration conforms to that of the head end 38 of the punch 26, and at the sametime the material of the slug flows laterally with respect to the axis 11 along which punch 26 advances at this time. As a result the laterally the punch '26, and as the punch 26 advances the head 38 1 thereof defines with the edge 17 at the upper end of the ring 3c an annular gap through which the slug material flows in the direction of advance of the punch 26 downwardly into the portion of the bore 4c which is above the projection 21 of the ejector punch 23 and in which the projection 24 is located. In this way the lower portion 20 of the spark-plug housing 2 of FIG. 3 is formed. The projection 24 contributes with the die ring 30 to the precise formation of the lower part 2c of the spark-plug housing. During the flow of the material of the slug 1 in the direction of advance of the punch 26 along its working stroke into the bore portion 4!: to form the base portion 20 of the article 2, the material of the slug 1 also flows in a direction opposite to the direction of advance of the punch 26 through the gap between the projection 36 of the punch and the inner surface of the intermediate ring 312 which forms the intermediate cavity portion 4b, and this material which flows through the latter gap in a direction opposite to the direction of movementof the punch 26 enters into the bore portion 4a of relatively large diameter. In this way the cylindrical intermediate portion 2a. becomes elongated and the already formed hexagonal portion 2b approaches the edge 15 at the top end of the die cavity 4, while the yieldable means P yields so that the guide sleeve 41' at this time moves in a direction opposite to the punch 26 with respect to the latter outwardly of the die cavity. Thus, the punches cooperate with the die means 3 to form a double-cup-shaped article which becomes elongated at its intermediate portion 2a by the flow of the material in a direction opposite to that in which the punch 26 moves along its working stroke.

As was pointed out above, because the punch 26 is guided by the sleeve 41 which is in turn guidedby the die means itself, any irregularity in the slug will not disturb the coaxial relationship of the punch 26 with respect to the die means 3 when the head 38 of the punch 26 enters into the slug 1.

During the advance of the punch 26 along its working stroke, it will move downwardly with respect to the guide sleeve 41, and, of course, the cylindrical projection 36 will move out of the guide sleeve 41. Thus, from the time when the projection 36 moves downwardly out of the sleeve 41 the punch 26 is guided only by the projection 39 which still remains inslidable engagement with the inner surface of the sleeve 41. However, in the meantime the cup-shaped configuration of the slug has been formed sufficiently so that the entire head 38 of the punch 26 is located within and centeredby the slug itself when the projection 36 moves beyond the guide sleeve 41, so that even at this time the coaxial relationship between the punch 26 and the die means 3 is maintained.

When the punch 26reaches the end of its working stroke, the parts have the position indicated in FIG. 2B, and at this time the shaping of the slug 1 into the sparkplug housing 2 shown in FIG. 3 is completed. It will be noted that the entire deformation of the slug '1 into the article shown in FIG. 3 takes place-in a single operation. During the initial part of the return stroke of the punch '26, the yieldable means P maintains the guide sleeve 41 and the-article 2 stationary with respect to the punch 26, as a result of the force exerted by the yieldable means P, so that in this way the article is stripped from the punch 26 during the return stroke thereof. The punch 26 will continue to move along its return stroke with respect to the sleeve 41 to the full extent determined by the limiting means 44, 39, and when the projection 39 engages the inner ends 44a of the screws 44, the sleeve 41 will not be able to remain stationary and thereafter the sleeve 41 will move with the punch 26 along the return stroke thereof.

The ejector punch 23 is now actuated in a known way by the structure which grips the portion 25 thereof so as to advance further into the die cavity and thus eject the completed article 2 from the die. Of course, the punch 26 and the sleeve 41 in the meantime have moved away from the die by a distance sufficient to enable the article 2 to be freely ejected from the die 3 through the upper end of the cavity thereof. Thereafter the punch 23 is returned in a known way to the position shown in FIG. 2 in preparation for the next cycle of operations.

The press operates in such a way that one cycle starts as soon as the previous cycle has endede and when the punch 26 reaches the end of its return stroke it will then start on the next working stroke, andduring the end of the return stroke of the punch 26 the ejected article is removed and a new slug 1 is placed in the die means 3 to be acted upon by the punch 26 as it moves downwardly along its next working stroke.

If, for any reason, the structure should not operate properly, then it is possible to actuate through the lever 52 a switch means 53, 54 which will be capable of stopping the operation of the press so thatthe punch 26 will not proceed along its next working stroke. 52 forms a switch-actuating means which operates in a manner described below for actuating the switch means 53, 54 only in the event that the operations do not proceed in the normal way and thus the actuation of the switch means 53, 54 can be used to signal the fact that the opera Thus, the lever member 53 of the switch 54 is urged by a spring 53' to its switch-closing position bridging a pair of stationary contacts of the circuit. Thus, with the parts in the position illustrated, whenever the main switch 55 is closed, the press will operate. However, whenever the free end 52' of the lever 52 engages the switch member 53 and moves it in opposition to the spring 53' to a position opening the switch 54, the motor M will automatically stop operating, and thus the operation of the press will stop, even though the main switch 55 remains closed.

Thus, for example, it may happen that sleeve 41 will start to move with the punch 26 along the return stroke thereof before the punch 26 has moved along its return stroke with respect to the sleeve 41 to the full extent determined by the limiting means 39, 44. This may happen in a special case where the force of the yieldable means P is insufiicient to maintain the sleeve 41 stationary with the force required to strip the article from the punch 26 during the return stroke thereof. In such a case the motion transmitting means 45, 48, 49 will turn the switch-actuating means 52 so that it will actuate the switch 53, 54 and automatically stop the drive of the plunger which is operatively connected to the working plate 29. If, however, the operations proceed normally so that the punch 26 moves along its return stroke with respect to the sleeve 41 to the full extent determined by the limiting means 39, 44, then the end 52 of the lever 52 is maintained at a distance from the switch means 53, 54 which is suificiently great to prevent the switch means from being actuated or engaged by the end 52' of the lever 52. -If the projection 39 engages the inner ends 44a of the screws 44, then when the punch 26 reaches the end of its return stroke the motion transmitting means will have turned the lever 52 through an angle which is too small to cause the end 52' of the lever 52 to actuate the switch means. On the other hand, if the sleeve 41 moves rearwardly with the punch 26 before the projection 39 engages the screws 44, then the elevation of the sleeve 41 will be greater than the elevation it has at the end of the return stroke of the punch 26 when the projection 39 engages the screws 44, and thus the motion transmitting means 45, 48, 49 will have turned the lever 52 through a greater angle so as to displace it through a distance sufiicient to actuate the switch 53, 54. Thus, this construction acts automatically to prevent the punch 26 from proceeding along its next working stroke in the event that the finished article 2 has not been properly stripped from the head end 36, 38 of the punch, and in this way the structure is protected against damage which in some cases might be irreparable.

After a slug 1 has been formed into the article 2 which is shown in FIG. 3, with the process and apparatus of the invention, normal, well known further operations are performed on the article such as piercing the partition between the pair of cup-shaped portions of the housing 2, providing one or two indentations at the exterior surface of the article, providing a thread on the base portion 20, knurling the intermediate portion 2a, and providing a flange along an edge of the head portion 2b of the article.

Of course, when the slug 1 is initially sheared from the rod, the slug should have a certain predetermined volume, but because of the unavoidable deformations in the slug 1 during the shearing thereof there are unavoidable small variations from this ideal predetermined volume of the slug, and the result is that there may be slight variations in the length of the hollow, cylindrical intermediate portion 2a of the finished article, so that the height of the entire housing 2 may be some-what smaller or somewhat greater depending upon inaccuracies which are unavoidable in the volume of the slug 1. However, the remaining portions of the article 2 are uniformly maintained at the precisely desired cross sections and dimensions and with precisely the desired configurations, and these latter requirements with respect to configurations and cross sections as well as dimensions are in no way influenced by slight variations in the height of the final article.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of metal-forming process and apparatus differing from the types described above.

While the invention has been illustrated and described as embodied in cold-shaping process and apparatus, it is not intended to be limited to the details shown, since various modifications and structural changes maybe made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a cold-pressing apparatus, in combination, annular die means having an inner annular surface coaxially surrounding the axis of said die means and defining a cavity therein; elongated punch means coaxial with said die means and movable axially with respect to said die means into said cavity during a working stroke of said punch means and out of said cavity during a return stroke of said punch means; a guide sleeve coaxially surrounding and slidably engaging said punch means and extending into said cavity and slidably engaging said inner surface of said die means so that said sleeve maintains the coaxial relationship between said punch means and die means during the working stroke of said punch means; biasing means operatively connected to said sleeve for urging said sleeve along the axis of said die means in the direction of said cavity with a force which increases in response to progressive displacement of said punch means in said direction so that after a slug has been shaped by said punch means in said cavity of said die means said sleeve by engaging the slug and as a result of said yieldable means will prevent movement of this slug with said punch means during the return stroke of the latter so that the slug will be stripped from said punch means; and limiting means carried in part by said sleeve and in part by said punch means for limiting the extent of movement of said punch means along said return stroke thereof with respect to said sleeve, whereby when said punch means has moved along its return stroke with respect to said sleeve to the limit determined by said limiting means, said sleeve will during the further movement of said punch means along its return stroke move with the latter away from said cavity.

2. In a cold-pressing apparatus, in combination, annular die means having an inner annular surface coaxially surrounding the axis of said die means and defining a cavity therein; elongated punch means coaxial with said die means and movable axially with respect to said die means into said cavity during a working stroke of said punch means and out of said cavity during a return stroke of said punch means; a guide sleeve coaxially surrounding and slidably engaging said punch means and extending into said cavity and slidably engaging said inner surface of said die means so that said sleeve maintains the coaxial relationship between said punch means and die means during the working stroke of said punch means; yieldable means operatively connected to said sleeve for urging the latter along the axis of said die means into said cavity thereof so that after a slug has been shaped by said punch means in said cavity of said die means said sleeve by engaging the slug and as a result of said yieldable means will prevent movement of this slug with said punch means during the return stroke of the latter so l 1 that the slug will be stripped from said punch means; limiting means carried in part by said sleeve and in part by said punch means for limiting the extent of movement of said punch means along said return stroke thereof with respect to said sleeve, whereby when said punch means has moved along its return stroke with respect to said sleeve to the limit determined by said limiting means, said sleeve will during the further movement of said punch means along its return stroke move with the latter-away from said cavity; stationary switch means; and switchactuating means operatively engaging said sleeve for movement in response to axial movement of said sleeve, said stationary switch means being located at too great a distance from said switch-actuating means to be engaged and actuated thereby when said punch means has moved along its return stroke with respect to said sleeve to the full extent determined by said limiting means While if for any reason said sleeve moves together with said punch means along the return stroke of the latter before said punch means has moved along its return stroke with respect to said sleeve to the full extent determined by said limiting means said actuating means will be moved by said sleeve through a distance sufiiciently great to engage and actuate said switch means, whereby said switch means will be capable of automatically signalling the fact that the punch means has not moved along its return stroke with respect to said sleeve to the full extent determined by said limiting means.

3. In a cold-pressing apparatus, in combination, annular die means having an inner annular surfacesurrounding the axis of said die means and defining a cavity therein; elongated punch means coaxial with said die means and extending into said cavity thereof during working of a slug therein, said elongated punch'means being movable axially with respect to said die means into said cavity thereof during a working stroke of said punch means and out of said cavity during the return stroke of said punch means; an elongated guide sleeve coaxially surrounding and slidably engaging said punch means, said sleeve extending into said cavity and slidably engaging said inner surface of said die means so that said sleeve will maintain the coaxial relationship between saidpunch means and die means; an elongated lever extending across the axis of said die means; support means supporting said lever for turning movement about an axis perpendicular to the axis of said die means; switch means located in the path of turning movement of said lever to be engaged and actuated thereby; yieldable means engaging said lever and urging the latter toward said sleeve; and motion transmitting means located between and engaging said sleeve and said lever for transmitting motion therebetween, whereby the yieldable means acts through said lever and motion transmitting means on said sleeve for urging the latter axially into said cavity; and limiting means carried in part by said sleeve and in part by said punch means for limiting the movement of the latter along its return stroke with respect to said sleeve, so that after said punch means has moved along its return stroke with respect to said sleeve to the limit determined by said limiting means said sleeve will move together with said punch means during the remainder of the return stroke thereof, the extent of movement of said lever during the return stroke of said punch means when the latter has initially moved with respect to said sleeve to the full extent determined by said limiting means, being insufficient to place said lever in engagement with said switch means while when said sleeve moves together with said punch means for any reason during the return stroke thereof before said punch means has moved along its return stroke with respect to said sleeve to the full extent determined by said limiting means,

said motion transmitting means will transmit movementfrom said sleeve to said lever for moving the latter through a distance suflicient to engage and actuate said switch means, whereby the latter may be used as a control to interrupt the operation of the press and prevent further movement of the punch means along its next working stroke.

4. In a cold-pressing apparatus, in combination, an-

nular die means having an inner annular surface coaxially surrounding the axis of saiddie means and defining a cavity therein; elongated punch means coaxial with said die means and movable axially with respect to said die means into said cavity during a working stroke of said punch means and out of said cavity during'a return stroke of said punch means; a guide sleeve coaxially surrounding and slidably engaging said punch means and extending into said cavity and slidably engaging said inner surface of said die means so that said sleeve maintains the coaxial relationship between said punch means, and die means during the workingstroke of said punch means; yieldable means operatively connected to said sleeve for urging the latter along the axis of said die means into said cavity thereof so that after a slug has been shaped by said punch means in said cavity of said die means said sleeve by engaging the slug and as a result of said yieldable means will prevent movement of this slug with said punch means during the return stroke of the. latter so that the slug 1 will be stripped from said punch means; limiting means carried in part by said sleeve and in part by said punch means for limiting the extent of movement of said punch means along said return stroke thereof with respect to said sleeve, whereby when said punch means has moved along'its return stroke with respect to said sleeve to the limit determined by said limiting means, said sleeve will during-the further movement of said punch means along 'its return stroke move with the latter away from said References Cited by the Examiner UNITED STATES PATENTS 427,43 5 5/ 1890 Manville 72-3 44 2,261,304 11/ 1941 Sparke 72-344 2,726,560 12/ 1955 Roux 72-345 2,748,932 6/1956 Kaul 72358 CHARLES W. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner. 

1. IN A COLD-PRESSING APPARATUS, IN COMBINATION, ANNULAR DIE MEANS HAVING AN INNER ANNULAR SURFACE COAXIALLY SURROUNDING THE AXIS OF SAID DIE MEANS AND DEFINING A CAVITY THEREIN; ELONGATED PUNCH MEANS COAXIAL WITH SAID DIE MEANS AND MOVABLE AXIALLY WITH RESPECT TO SAID DIE MEANS INTO SAID CAVITY DURING A WORKING STROKE OF SAID PUNCH MEANS AND OUT OF SAID CAVITY DURING A RETURN STROKE OF SAID PUNCH MEANS; A GUIDE SLEEVE COAXIALLY SURROUNDING AND SLIDABLY ENGAGING SAID PUNCH MEANS AND EXTENDING INTO SAID CAVITY AND SLIDABLY ENGAGING SAID INNER SURFACE OF SAID DIE MEANS SO THAT SAID SLEEVE MAINTAINS THE COAXIAL RELATIONSHIP BETWEEN SAID PUNCH MEANS AND DIE MEANS DURING THE WORKING STROKE OF SAID PUNCH MEANS; BIASING MEANS OPERATIVELY CONNECTED TO SAID SLEEVE FOR URGING SAID SLEEVE ALONG THE AXIS OF SAID DIE MEANS IN THE DIRECTION OF SAID CAVITY WITH A FORCE WHICH INCREASES IN RESPONSE TO PROGRESSIVE DISPLACEMENT OF SAID PUNCH MEANS IN SAID DIRECTION SO THAT AFTER A SLUG HAS BEEN SHAPED BY SAID PUNCH MEANS IN SAID CAVITY OF SAID DIE MEANS SAID SLEEVE BY ENGAGING THE SLUG AND AS A RESULT OF SAID YIELDABLE MEANS WILL PREVENT MOVEMENT OF THIS SLUG WITH SAID PUNCH MEANS DURING THE RETURN STROKE OF THE LATTER SO THAT THE SLUG WILL BE STRIPPED FROM SAID PUNCH MEANS; AND LIMITING MEANS CARRIED IN PART BY SAID SLEEVE AND IN PART BY SAID PUNCH MEANS FOR LIMITING THE EXTENT OF MOVEMENT OF SAID PUNCH MEANS ALONG SAID RETURN STROKE THEREOF WITH RESPECT TO SAID SLEEVE, WHEREBY WHEN SAID PUNCH MEANS HAS MOVED ALONG ITS RETURN STROKE WITH RESPECT TO SAID SLEEVE TO THE LIMIT DETERMINED BY SAID LIMITING MEANS, SAID SLEEVE WILL DURING THE FURTHER MOVEMENT OF SAID PUNCH MEANS ALONG ITS RETURN STROKE MOVE WITH THE LATTER AWAY FROM SAID CAVITY. 